The present invention relates generally to printed circuit cards, and more specifically to printed circuit card assemblies having controlled expansion properties.
Rapid advances in technology and increasing consumer demand are driving manufacturers and suppliers of electronics systems to increase the density of circuit cards, and to populate the circuit cards with larger and larger circuit devices. Typical modem circuit cards are densely populated with large and complex integrated circuits, such as microprocessors and supporting chipsets.
As circuit devices such as microprocessors increase in size, the likelihood of solder joint failure increases due to a mismatch in coefficients of thermal expansion between devices and cards. For example, if a large microprocessor is surface mounted to a circuit card, solder connections exist across the width and length of the microprocessor. If the microprocessor has a coefficient of thermal expansion different from the coefficient of thermal expansion of the circuit card to which it is mounted, the microprocessor package and the circuit card expand and contract different amounts as a function of temperature. As a result, interconnect failures can result at solder joints.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a method and apparatus to control thermal expansion properties of circuit card assemblies.